Cerebral Toxoplasmosis Mimicking a Brain Neoplasm in an Inaugural HIV-Positive Patient: The Importance of Early Decision-Making and Background Assessment in the Emergency Department.

Intracranial lesions can present a diagnostic challenge in patients without previously known immunosuppression. When focal neurological signs and seizures occur in a patient with no established medical history, an expansive brain lesion may be initially interpreted as a neoplasm, influencing early clinical decisions regarding the extent of supportive measures. However, opportunistic infections, such as cerebral toxoplasmosis, should remain on the differential diagnosis - particularly after consideration of the patient's background and potential epidemiological risks. We present the case of a middle-aged woman of African origin who presented with new-onset seizures and a prolonged history of anorexia and weight loss. Initial neuroimaging suggested a primary or metastatic brain tumor, raising concerns regarding the patient's prognosis and the appropriateness of aggressive support in the emergency setting. The patient received corticosteroids and anticonvulsants in the emergency department (ED), with a subsequent need to start noninvasive ventilation. Further laboratory workup revealed the inaugural human immunodeficiency virus (HIV) and infection rather than a neoplastic process. Following targeted antimicrobial therapy and initiation of antiretroviral treatment (ART), she demonstrated remarkable neurological and functional recovery. This case underscores the importance of maintaining a broad differential diagnosis in the ED, performing a thorough background evaluation of patients, and sustaining supportive management until a definitive diagnosis is established.